False positive gpl license detection

[pombredanne]

This file https://github.com/boostorg/assign/blob/develop/include/boost/assign/ptr_list_of.hpp#L195

                    -   score: '50.0'
                        start_line: 227
                        end_line: 227
                        matched_length: 1
                        match_coverage: '100.0'
                        matcher: 2-aho
                        license_expression: gpl-1.0-plus
                        rule_identifier: gpl_bare_word_only.RULE
                        rule_url: https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/gpl_bare_word_only.RULE
                        matched_text: gpl;
                    -   score: '50.0'
                        start_line: 228
                        end_line: 228
                        matched_length: 1
                        match_coverage: '100.0'
                        matcher: 2-aho
                        license_expression: gpl-1.0-plus
                        rule_identifier: gpl_bare_word_only.RULE
                        rule_url: https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/gpl_bare_word_only.RULE
                        matched_text: gpl(
                    -   score: '50.0'
                        start_line: 229
                        end_line: 229
                        matched_length: 1
                        match_coverage: '100.0'
                        matcher: 2-aho
                        license_expression: gpl-1.0-plus
                        rule_identifier: gpl_bare_word_only.RULE
                        rule_url: https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/gpl_bare_word_only.RULE
                        matched_text: gpl;